Why can I see some lemmy.world communities but not others coming from kbin.social?

Basically title. As you can see, I see this community and can post to it fine. But some others just return a 404.

This is the link that works (for kbin.social):
https://kbin.social/m/nostupidquestions@lemmy.world

And here's one that doesn't:
https://kbin.social/m/imperor@lemmy.world
actual link: https://lemmy.world/c/imperor

Any input/Help would be appreciated!